The antiviral agent of the subject invention is produced concomitantly with antibiotic U-44,590. The fermentation conditions and characteristics of the producing microorganism are disclosed in U.S. Pat. Nos. 3,907,643 and 3,907,779. There is no disclosure of the production of antiviral U-50,228 in these patents.
U-50,228 has been determined through structural studies to be 1-methylpseudouridine. Pseudouridine is a known compound having been isolated in 1958 from hydrolysates of "soluble ribonucleic acids". (The Chemistry of Nucleosides and Nucleotides by A. M. Michelson, Academic Press, New York 1963, p. 12).
In the course of structural studies with pseudouridine, Waldo E. Cohn, J. Biol. Chem., 235, 1488 (1960) reacted pseudouridine with diazomethane. The reaction mixture was characterized by paper chromatography; there was no isolation of products. On the basis of R.sub.f values and UV, tentative structures for the three compounds observed in the papergrams where assigned. One of these tentative structures was for 1-methylpseudouridine. Similarly, J. P. Scannell, A. M. Crestfield and F. W. Allen reported in Biochim. et. Biophys. Acta, 32, 409 (1959) that they methylated pseudouridine using dimethylsulfate. A mixture of six "methylated pseudouridine derivatives" was resolved by paper chromatography. By comparison with the methylation reaction products obtained from uridine and uracil the authors concluded that two NH-groups in pseudouridine are "free" and that the ribose moiety is attached to carbon. As disclosed above, the compound of the subject invention was not isolated and, therefore, not characterized in any of the known prior art publications.